Leases (Components Of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 3,718	$ 3,767
Short-term lease expense	21,125	17,265
Lease expense, gross	24,843	21,032
Less: Sublease income	170	329
Total lease expense	$ 24,673	$ 20,703
Minimum
Lessee, Lease, Description [Line Items]
Short term lease, lease term	1 month
Maximum
Lessee, Lease, Description [Line Items]
Short term lease, lease term	1 year